Shoe stiffener



Patented Sept. 1, 1925.

UNITED STATES PATENT OFFICE.

ALBERT L. CLAPP, OF DANVERS, MASSACHUSETTS, ASSIGNOR TO BECKWITHZlYIANU-- FACTURING COMPANY, OF BOSTON, MASSACHUSETTS, A CORPORATION OFMAINE.

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To all whom it may concern:

Be it known that I ALBERT L. CLAPP, a citizen of the United States,residing at Danvers, in the county of Essex and State of Massachusetts,have invented new and useful Improvements in Shoe Stiflt'eners, of whichthe following is a specification.

This invention has for its object to produce a fibrous materialcontaining a thermo. plastic compound, for use as a shoe stifl'ener,such as a. box toe or box-toe blank,the more especial object being toprovide a material of the class referred to which may be manufactured bythe aid of the machinery common to the manufacture of paper.-

It has been almost the universal practice in the manufacture of suchthermo-plastic or moldable box toes, first to form a fibrous sheetusually of wool or cotton and Wool felt, then to saturate or impregnatethe sheet with a molten th enno-plastic compound or mixture, and, afterthe latter has cooled and set, to cut box-toe blanks of appropriate sizeand Shape therefrom. A box-toe blank thus formed has certain highlydesirable characteristics flowing from the nature of the fibrous sheet.Since the sheet is a true felt, with numerous pores and interstices, ithas the capacity for absorbing and carrying a large amount,proportionate to its weight, of the thermo-plastic compound; and,because, of the long fibers of which it is composed, it may (when itscontained thermo-plastic compound is fluxed or plastic) be stretchedabout the toe end of the last Without dan er of tearing But the processof producing felt by the usual or common felting machine is a long andexpensive operation and the output. is limited.

Any stiffened, or moldable box toe mate-' rial must be capable of beingstretched without tearing sufliciently to permit its being drawn aboutthe last in the pulling-over and end-lasting operations; that is, itmust be possessed of a certain degree of tensile strength and et must becapable of being stretched, and toughness and durability. A,

After many experiments, I have succeeded in producing from an aqueouspulp a box toe material having the thermo-plastic com- 1 poundincorporated therein and possessing the necessary qualities' andcharacteristics hereinbefore referred to. This material,

at the same time Application filed December 21, 1922. Serial' No.608,358.

which is sheeted on a common paper-making machine of the cylinder type(i. e. awet machine), contains a very large-percentage of thethermo-plastic stiffening compound, may be stretched and molded aboutthe end of the last without danger of being torn in the stretchingoperation, and possesses that stiffness and resiliency which isnecessary to produce a successful box toe.

The t-hermo-plastic compound is incorporated in the pulp prior to theformation of the sheet,

and one of the problems to be solved in accomplishing this result is toefl'ect the retention of the thermo-plas'tic compound in the pulp. l v vThe pulp must be made of those'materials which-will impart to thefinished sheet the optimum characteristics hereinbefore referred to. touse ce'llulosic material or wood pul together with long hairs such ascattle ha1r or wool. It is recognized by paper manu- I have found thatit is possible facturers that the stock must be capable of being formedon the cylinder mold and built up on the make-up roll, and that it mustbe of such character as will permit the incorporation of several timesits weight of the thermo-plastic compound. The

thermo-plastic compound must be of such character that it may bepowdered or finely reduced, that it should possess a relatively shortmelting-point-lag so that it will set rapidly, when cooled after oncebein in molten condition, and, that it shoul be capable of beingsoftened upon the application of moderate heat. As the thermoplasticcompound, I may use various bitumens, resins, gums and waxes invaryinghaving the characteristics last referred to, are comprehendedwithin the phrase.

thermo-plasticcompound.

from those hereinbefore' The following example will serve to illustratea box-toe material embodying the invention and the process of producingit.

5 parts of cellulosic material, such as sul- I phate or sulphite pulp orwaste kraft or sulengine together with sufficient water to ensure thecirculation of the stock, and are beaten until the leather has partiallydissolved and the cellulose fibershave been more or less hydrated. Whilethe leather is artly dissolved, a small uantity of gelatmous fibrousleather resi uum remains. now add to the -beater about 5 parts of cattlehair (or wool), and, lifting the beater roll from the bed plate, Ioperatethe beating engine until the hair is thoroughly mixed into thestock. It is desirable. not to cut the hair into short pieces but toleave it in relatively long condition, preferably so that it retains itsoriginal length. I now add to the stock a large amount of the finely-.divided thermo-plastic compound, say from 90 to 120 parts thereof, andthe operation of the beater is continued until the thermoplasticcompound has been thoroughly distributed throughout the stock. In\ theparticular example given, I ordinarily employ about 90 parts of a blendor mixture consisting of certain ingredients in the followingproportions; namely, about 80% of acid resins of which aboutone-sixth'is copal and the remainder rosin, about 15% montan wax, about3% china wood oil, and about 2% of lime. These ingredients arethoroughly mixed together when molten and the lime reacts with certainacids of the resins to form a calcium resinate or soap.

After the thermo-plastic compound is thoroughly incorporated in anddistributed throughout the pulp, I add about 20' parts of aluminum sulhate and the stock is further beaten unt1l the alum is distributedthroughout the pulp and has precipitated the 'dissolved leather in theform of a gelatinous hydrate which coagulates or precipitates and fixesupon the fibers the particles of thermo-plastic compound which are inthe stock. Thev aqueous pulp is now transferred to a paper-makingmachine and formed into sheets of the desired caliper. Each sheet asstripped from the make-up roll is dried flat and then subjected tosufficient heat and pressure to melt the contained thermo-plasticcompound and cause it to penetrate throughout and coalesce within thesheet. To accomplish this result, the sheet niay be passed throughcalender rolls heated to the necessary temperature. The sheet is now cutinto blanks of appropriate size and shape to serve as shoe stifl'eners,such, for example, as box toes or counter stiifeners. v

I may incorporate .in the aqueous pulp.

terial an /or to act as a filler.

I the fibers so that only a relatively small proportion of thedisintegrated thermo-plastic compound escapes with the white water. Thefibrous leather residium aids in forming the sheet on the wet machineand increases the strength of the resulting sheet. The presence of thelong hairs in the stock permits the stock to be stretched and moldedwithout being sheared or torn in the molding operation, whereas thecellulose fibers are necessary to give suflicient strength and formationto the sheet.

A box-toe blank, formed as herein de scribed, possesses thosecharacteristics "and qualities which enable it to be successfully usedin lieu of those heretofore produced, in which the felt is saturatedWith molten thermo-plastic compound, but may be pro.- duced in verylarge quantities and at relatively low, expense. The fibrous materialswhichv are utilized are of themselves inexpensive; namely, chemical.wood pulp, cattle hair and other scrap. If sulphite or sulphatescreenings be used, substantially all of the fibrous materials are ofthe nature of waste materials or by-products.

In the foregoing description it will be observed that the proportion ofthermoplastic compound "to the cellulosic material and the hair is about9 to 1 by weight, and, in fact, it may be even greater. finishedproduct, the ratio of thermo-plastic compound to fibers is as 7.5to-1,-a result which, so far as I know, has never before been achieved.Consequently the box toe when molded possesses, to a maximum degree,stiffness, toughness and resiliency, so

that its shape isnot easily distorted when.

incorporated in a shoe. The box-toe blank may be skived to present asharp edge,

-which of itself is highly desirable in. the

In the .i

a precipitate flexible upon the application of heat-and 3. A shoestiffener adapted to be made limp and flexible upon the application ofthe fibers being in heat and comprising cellulose fibers, cattle hair,leather fibers, and thermo-plastic compound, and a precipitate formed bythe reaction of a precipitant with dissolved leather, felted relationand the thermo-plastic compound being distributed throu hout the fibers.

'4. g process of making shoe stifl'eners, which comprises pulpingcellulose fibers, leather in the presence of caustic soda, long fiberssuch as" cattle hair, divided thermo-plastic compound, then adding aprecipitating agent for the dissolved leather, and sheetmg the resultantpulp on a 'paper machine.

water,

and a finely- 5. A process of making a shoe stiffener, which comprisesbeating together. cellulose fiber, tanned leather and caustic soda inuntil the leather is more or less dissolved, incorporating'long fibersand finelydivided or crushed thermo-pla'stic compound in the resultingpulp, addin a precipitating agent for reaction with the issolvedleather,

and sheeting the pulpy mass on .a paper machine.

6..A process of making a fibrous 'inaterial suitable for shoestifieners, which comprises forming an aqueous fibrous pulp,mcorporating a crushed thermo-plastic compound in the pulp, in theproportion of not less than six parts by weight of said compound to onepart by weight of fibers, coagu ating and fixing the thermo-plasticcompound on the fibers, and sheeting the resulting pulp in a papermachine.

In testimony whereof I have aflixed my signature.

- .ALBERT L. CLAPP.

